A gas turbine engine generally includes a fan and a core arranged in flow communication with one another. Additionally, the core of the gas turbine engine generally includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is provided from the fan to an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are routed from the combustion section to the turbine section. The flow of combustion gases through the turbine section drives the turbine section and is then routed through the exhaust section, e.g., to atmosphere.
Typically, the combustion section includes a combustor having a combustion chamber defined by a combustor liner. Downstream of the combustor, the turbine section includes one or more stages, for example, each stage may contain a plurality of stationary nozzle airfoils as well as a plurality of blade airfoils attached to a rotor that is driven by the flow of combustion gases against the blade airfoils. The turbine section may have other configurations as well. In any event, a flow path is defined by an inner boundary and an outer boundary, which both extend from the combustor through the stages of the turbine section.
Conventionally, the inner and outer boundary structures defining the flow path have been formed of separate components. For example, an outer liner of the combustor, a separate outer band of a nozzle portion of a turbine stage, and a separate shroud of a blade portion of the turbine stage usually define at least a portion of the outer boundary of the flow path. However, utilizing separate components to form each of the outer boundary and inner boundary requires a greater number of parts. By reducing the number of components and corresponding gaps between components, the parasitic leakages are reduced and the engine efficiency is improved. Therefore, flow path assemblies may be utilized that have a unitary construction, e.g., a unitary outer boundary structure, where two or more components of the outer boundary are integrated into a single piece, and/or a unitary inner boundary structure, where two or more components of the inner boundary are integrated into a single piece.
A unitary construction of such flow path components can be furthered by assembling turbine nozzle airfoils, which also may be referred to as stator vanes, with the outer boundary structure and the inner boundary structure. In some instances, the nozzle airfoils can be inserted and secured to one or both of the outer and inner boundary structures. Conventionally, inserting a turbine nozzle airfoil into a boundary structure has been challenging. In particular, conventional methods for securing nozzle airfoils to a boundary structure and sealing the nozzle airfoil with the structure to prevent flow path leakages have been unsatisfactory.
Accordingly, improved methods for assembling flow path assemblies would be desirable. More particularly, improved methods for assembling airfoils with a boundary structure would be beneficial. Additionally, a flow path assembly formed by such methods would be useful.